using System.Collections;

namespace Qrakhen.Qamp.Core.Collections;

public class PopStack<T> : IEnumerable<T>, IPop<T>, IPeekable<T>
{
    private readonly T[] _data;

    private int _position;

    public int Position => _position;
    public int Length => _data.Length;
    public bool Done => _position >= _data.Length;

    public PopStack(IEnumerable<T> data)
    {
        _data = data.ToArray();
        _position = 0;
    }

    public T Pop() => _data[_position++];

    public T Peek(int delta = 0) => _data[_position + delta];

    public bool CanPeek(int delta = 0) 
        => _position + delta > -1 && _position + delta < _data.Length;

    public IEnumerator<T> GetEnumerator()
    {
        foreach (var item in _data)
            yield return item;
    }

    IEnumerator IEnumerable.GetEnumerator()
        => GetEnumerator();
}